Saturable reactor for correcting raster distortion

ABSTRACT

A saturable reactor comprising an H-shaped core on which are wound two coils, each coil being divided respectively into two coil parts and each coil part being constituted of symmetrical winding on the left and right arms of a yoke with the coupling part formed on the middle of the aforementioned core as the center. One of the aforementioned coils is constituted so that the magnetic flux generating direction of the pair of coil parts wound on the yoke mentioned above would be identical, while the other coil mentioned above is constituted so that the magnetic flux generating direction of the pair of coil parts wound on the yoke mentioned above would be mutually opposite.

United States Patent 1 [111 3,716,748

Sohoma 1 Feb. 13, 1973 541 SATURABLE REACTOR FOR 3,440,483 4/1969 Kaashoek et al ..315 27 SR CORRECTING R S ER DISTORTION 3,444,422 5/1969 Wolber ..315 27 SR [75] Inventor: fg s Sohoma Funabashi Primary Examiner-Benjamin A. Borchelt 3 re ecture Japan Assistant Examiner-R. Kinberg [73] Assignee: Denki ()nkyo C Ltd Tok AttorneyJames E. Armstrong and Ronald S. Cornell Japan [22] Filed: July 29, 1970 [21] Appl. No.: 59,155

[57] ABSTRACT A saturable reactor comprising an H-shaped core on which are wound two coils, each coil being divided respectively into two coil parts and each coil part [30] F i A li ti n P i it D t being constituted of symmetrical winding on the left and right arms of a yoke with the coupling part July 24,1969 Japan ..44/73474 formed on the middle of the aforementioned core as the center. One of the aforementioned coils is cong y' "315/27 a stituted so that the magnetic flux generating direction I g 9 E of the pair of coil parts-wound on the yoke mentioned [5 med 0 can 1 /2 above would be identical, while the other coil men- R f d tioned above is constituted so that the magnetic flux 1 e erences generating direction of the pair of coil parts wound on UNITED STATES PATENTS the tyoke mentioned above would be mutually opposl e. 3,346,765 10/1967 Barkow ..3l5/27 SR 3,427,497 2/1969 Gostyn ..315/27 SR 5 Claims, 13 Drawing Figures 7 724 K I S I l 5 H U J0 f l SN .l I

PATENIEUFEBmms 3'716748 SHEET unr 4 FIG. 11

SATURABLE REACTOR FOR CORRECTING RASTER DISTOR'IION BACKGROUND OF THE INVENTION Pincushion type distortion of cathode ray tube dis plays has long been recognized. In black-and-white displays, this type of distortion is corrected to a considerable extent through the use of permanent magnets, which are so shaped and fixed in positions relative to the cathode as to produce an appropriate magnetic biasing effect on the cathoderay beam. In the case of color display tubes, which are based on the use of shadow mask or similar principles, however, fixed correcting magnets cannot be used.

One approach, which has been adopted in connection with the correction of pincushion distortion in color displays involves modulation or variation of one of the sweep currents in such a manner as to produce the desired results.

In the arrangement for correction of raster distortion occurring in the vertical direction (e.g., top and bottom pincushion distortion), the cyclically varying vertical scanning current must be modulated at a higher horizontal rate, such as by adding a horizontal rate correction current alternated parabolically to the vertical deflection current.

In the arrangement for the correction of raster distortion occurring in the horizontal direction (e.g., side pincustion distortion), the cyclically varying horizontal scanning must be varied at a lower vertical rate, since the magnitude of a horizontal scanning current is parabolical.

It has further been suggested in the prior art that this modulation be accomplished electromagnetically using a combination of magnetic and electrical circuitry which works on the principle of magnetic saturability.

In general, nominal correction can be produced by this means. There are many kinds of saturable reactor device and circuit connections for correcting pincushion distortion such as those described in US. Pat. Nos. 2,906,919, 3,346,765, and 3,444,422.

The existing reactor, as seen in the aforementioned US patents, is composed of a core that mutually couples the two ends of three parallel yokes, a coil is shuntwound on the two yokes on both sides of the said core in opposite winding direction and is connected in series, and another coil is wound on the center of the said core. Since the vertical deflection current has been applied to one of the above-mentioned coils and the horizontal deflection current has been applied to the other coil, the device has disadvantages as described herein.

In the manufacture of a reactor, coils are fitted to respective yokes of an E-shaped core, and I-shaped cores are coupled on the free ends of the yokes of the E-shaped core in order to magnetically couple the yokes. Using this process, the manufacturing process has been time-consuming, making it unsuited to massproduction. Magnetic flux leakage has been small, since the yokes formed a closed magnetic path. However, since current magnetic flux density in the closed magnetic path varied markedly depending on the inflnitesimal differences in the gaps in the magnetic path, the characteristics of individual products lost uniformity because of disparity in the gap arising in the coupled part of the E-shaped core and the I-shaped core.

The present invention offers saturable reactors extremely easy to assemble and manufacture and with uniform quality of individual products.

SUMMARY In accordance with the invention there is provided a saturable reactor comprising an H-shaped core composed of two parallel yokes and a coupling member that connects the midsections of the said yokes to form left and right arms on either side thereof. The I-I-shaped core has first and second coils wound aroundone of the i BRIEF DESCRIPTION OF THE DRAWINGS The invention is illustrated in detail in the accompanying drawings in which:

FIG. 1 is a front view of the reactor of the present invention.

FIG. 2 is a side view of the reactor shown in FIG. 1.

FIG. 3 is a front view of an embodiment of the reactor of the present invention; it shows a longitudinally sliced segment of the coil.

FIG. 4 is a side view of the reactor of FIG. 3.

FIG. 5 is a diagram of the reactor shown in FIG. 3.

FIG. 6 is a front view of another embodiment of the reactor of the present invention; it shows a longitudinally sliced segment of the coil. FIG. 7 is a side view of the reactor shown in FIG. 6.

FIG. 8a, FIG. 8b and FIG. 8c, are diagrams respectively of the reactor shown in FIG. 6.

FIG. 9 is a front view of another embodiment of the present invention.

FIG. 10 is a side view of the reactor shown in FIG. 9.

FIG. 11 is a front view of a modification of the embodiment of FIG. 9.

DETAILED DESCRIPTION Referring to FIGS. 1 and 2 of the drawings the reactor of the invention is composed of an I-I-shaped core 10, a first coil 20 and a second coil 30 wound around the said core and fixed permanent magnets 40 for magnetic biasing, which are attached to the core mentioned above.

The above-mentioned core 10 is composed of two parallel yokes ll, 12 and coupling part 13 that connects these yokes at their mid-section. The yokes 11, 12 form the yoke arms 11a, 11b and 12a, 12b on the left and right sides of the coupling member 13 which forms the central section.

Of the two coils mentioned above, the first coil 20 is divided into two serially connected coil parts 21, 21', and each coil part 21, 21' is separately wound around the left and right arms 11a, 11b (or 12a, 12b) of yoke 11 (or 12) mentioned above, the windings being in the same direction.

Of the two coils mentioned above, the second coil 30 is divided into two serially connected coil parts 31, 31, and each coil part 31, 31 is separately wound around the left and right arms 11a, 11b yoke 11, mentioned above on which the first coil is wound, the windings being in mutually opposite directions.

The first coil 20 and the second coil 30 are identical in use as those of the conventional reactor in that vertical deflection'current is caused to flow through'one and the horizontal deflection current is caused to flow through the other. This differs depending on whether the vertical distortion of the raster is to be corrected or the horizontal distortion is to be corrected. In other words, it differs according to the circuit to be connected to the reactor. And such circuits are already publicly known through prior techniques, such as are detailed in the aforementioned U.S. Patents.

Such being the reactor of this invention, flow of horizontal deflection current lh through the first coil 20 and of vertical deflection current Iv through the second coil 30 induces and superimposes the reverse correction current waveform of the horizontal deflection cycle on the vertical deflection current Iv. At the same time, since core is magnetically biased by the permanent magnet 40, the amplitude of the aforementioned reverse correction current waveform becomes large at the beginning and the end of the vertical scanning period and small at the center thereof. Also, since the coil parts 31, 31' of the second coil 30 are wound so as to be in mutually reverse phases, the phase of the correction current waveform becomes reversed at the beginning and the end of the vertical scanning period.

When the basic waves only of the reverse correction current are taken out with a tuning circuit, sine wave current of forward correction, i.e., correction current of waveform that can be substituted for the approximately parabolic current, is obtained. This allows correction of the vertical raster distortion. Since the operation and application of the reactor described in the foregoing are already publicly known through prior techniques, detailed descriptions will be omitted.

As has been clarified by the foregoing descriptions and diagrams, the reactor related to the present invention uses the H-shaped core 10, for which reason it offers the advantage of easy fitting of the first coil and the second coil 30 on the arms 11a and 11b of the yoke 11. Also, as the magnetic path is of the open type, it offers the advantage of the absence of any effect on the characteristics of individual products even when there are slight difference in the gaps between the pair of facile manner and of uniform characteristics of individual products.

In the embodiment shown in FIGS. 3 to 5, a reactor with fixed permanent magnet 40 and rotary movable magnet 50, which has greater excitation force than the fixed magnet, mounted on the H-shaped core 10 is shown.

The fixed magnet 40 mentioned above is mounted so that the magnetic pole will be adjacent to the arm 11a of that side of yoke 11 on which the coil is wound, while the movable magnet 50 mentioned above is rotatably mounted on the end of the yoke on the opposite side from the aforementioned fixed magnet 40.

The movable magnet 50 mentioned above is of disc form, is magnetizedin'the direction of the diameter and is made in such a way that the ends of the two yokes 1 l, 12 of the core mentioned above are in contact with the face of the disc.

The reactor shown in this embodiment has, as stated above, the fixed magnet 40 and the movable magnet 50 mounted on the two ends of core 10. For this reason, the yoke 11 of the core 10 with coil wound around it is given magnetic biasing by the two magnets 40 and 50, and at the same time, the magnetic biasing points of arms 11a, 11b of the yoke 11 can be made unequal by the rotation of the movable magnet 50.

In other words, if the magnetic pole touching the yoke 11 of the fixed magnet 40 is assumed to be N, the magnetic biasing points of arms 1 1a, 11b of the yoke 11 may be varied as hereunder described. As shown in FIG. 3, when the magnetic pole S of the movable magnetic 50 is brought into contact with the tip of the yoke 11, the magnetic fluxf that flows through the arm 11b becomes larger than the magnetic flux f that flows through the other arm 110, since the excitation force of the movable magnet 50 is greater than that of the fixed magnet 40. By this, the magnetic biasing point of the arm 1 1b becomes deeper than that of the arm 1 1a.

Also, as shown in FIG. 5, when the magnetic pole S of the movable magnet 50 is brought close to the yoke 12, the volume of the magnetic flux f that flows through the arm 11b becomes less than the magnetic flux f that flows through the other arm 11a. For this reason, the magnetic biasing point of arm 11b becomes shallower than that of the other arm 1 1a.

Consequently, since it is possible with the reactor of the present invention to make the amplitude of the above-mentioned correction current asymmetrical at the start and end of a vertical scanning period by means of the rotation of the movable magnet 50, it is possible to correct the vertical (top and bottom) distortion of the display when it is asymmetrical. With the reactor used for the embodiment it is, of course, possible to make the magnetic biasing points of arms 11a and 11b identical by means of the rotation angle of the movable magnet 50. The reactor may also be used for correcting the horizontal (left and right) distortions.

FIGS. 6 to 8 show a reactor with movable magnets 50, 50 mounted on the two ends of the core 10. While the pair of movable magnets 50, 50' mentioned above are of disc form, they are also magnetized in the direction of diameter. They are, moreover, mounted on the core in such a manner that they simultaneously touch the two yokes 11 and 12 of the core 10.

Consequently, the reactor shown in the embodiments of the invention cited above is magnetically biased by means of the pair of movable magnets 50, 50' and is capable of making the magnetic bias points of the two yoke arms Ila, 11b with coils wound around them simultaneously shallow and deep by the rotation of the movable magnets. In addition, the reactor is capable of making the magnetic biasing points of the two yoke arms 11a, 11b mentioned above relatively unbalanced. Adjustment of the magnetic biasing points of the reactor in the embodiments of the invention is accomplished as hereunder described.

To make the magnetic biasing points of the two yoke arms 11a, lllb identical, movable magnets 50, 50' are rotated, as shown in FIG. 8, so that magnetic poles of different polarity will come adjacent to the two ends of the yoke 11 on which coils are mounted. As this will make f and f magnetic fluxes that that flow through the yoke arms 11a and 11b of identical volume, correction of distortion becomes possible if the pincushion distortion in the vertical direction (top and bottom) or in the horizontal direction (left and right) is symmetrical. Also, when the above-mentioned pair of movable magnets 50, 50 are rotated in the same direction by the same angle, the volume of magnetic fluxesf and f that flow through the above-mentioned yoke arms 11a, and 1112 can be reduced by the same volume. By this means, the magnetic biasing points of the yoke arms 11a and 11b can be made shallower while maintaining the same relationship.

At the above condition, in other words, the magnetic biasing points of yoke arms 11a, 11b are deepest under the state shown in FIG. 8a and become shallower as the movable magnets 50, 50' are rotated.

As the magnetic poles of the movable magnets 50, 50' cease to face each other, when one or the other of the movable magnets is rotated, it becomes possible to make the magnetic biasing points of the two arms 11a, 11b of the yoke l l relatively unbalanced.

As shown in FIG. 8b, when the movable magnet 50 on the side of the yoke arm 11b is rotated to bring the magnetic pole S closer to the yoke 12, the magnetic flux f that flows through the yoke arm lla becomes larger than the magnetic flux f that flows through the other yoke arm 11b. Therefore, the magnetic biasing point of the yoke arm 11a can be made deeper than that of the yoke arm 11b. On the contrary, if the movable magnet 50' on the side of the yoke arm 11a is rotated, as shown in FIG. 8c, to bring the magnetic pole N closer to the yoke 12, magnetic flux j, that flows through the yoke arm 11a becomes less than the magnetic flux f, that flows through the yoke arm 11b, and the magnetic biasing point of yoke arm 11b can be made deeper. Consequently, if the movable magnet is rotated as in FIG. 8b and FIG. 8c, correction of vertical (top to bottom) and horizontal (left to right) pincushion distortion of asymmetrical form becomes possible. If, therefore, the reactor of the embodiments of the invention should be used, the absolute value of the degree of correction of symmetrical or asymmetrical pincushion distortion can be adjusted with the reactor itself.

In FIGS. 9 and 10, there is shown a reactor with a fixed magnet 40 and a movable magnet 50 mounted on the core 10 as in the case of reactor in FIG. 3. The

movable magnet 50 in the embodiment has an aperture 51 formed on the mid-section of its disc, and this aperture 51 is fitted onto the yoke arm 11b of the yoke 11 so as to allow rotation thereof which makes it possible to mount it on the core 10. A knob shaft 60 is fixed in the aperture 51 of the movable magnet 50, and turning of this knob shaft 60 executes rotation of the movable magnet 50.

In the embodiment, the reactor is housed in the easing made of an insulating material, and the knob shaft 60 protrudes out of the case 70.

The movable magnet 50 mentioned above is pressed against the core 10 with the leaf spring so that it will not undergo automatic rotation, while the lead-out wires of the first coil 20 and the second coil 30 are connected to terminals 71 of the case 70.

In the embodiment, arrangements are made so that the movable magnet 50 will rotate with yoke 11 of the core 10 as the pivotal point. Consequently, the mag netic flux f that flows through the yoke arm 11a of the yoke 11 is determined by which magnetic pole of the movable magnet 50 is closer to the yoke 12. In other words, if the magnetic pole N is now adjacent to yoke 11 of the fixed magnet 40, the magnetic flux f that flows through the yoke arm 11b is reduced when the pole S of the movable magnet 50 draws closer to yoke 12 but on the other hand, the magnetic fluxf that flows through yoke arm 11b increases as pole N of the movable magnet 50 draws closer to the yoke 12.

Consequently, the volume of magnetic flux f that flows through the yoke arm 11b can be varied by the rotation of the movable magnet 50. As a result, it is possible to make the volume of magnetic flux f that flows through the yoke arm 11b identical with that of magnetic flux f that flows through the yoke arm 110, or to make the volume of magnetic flux f either larger or smaller than the magnetic flux f,.

The movable magnet shown in the present embodiment may also be applied to the reactor shown in FIG. 6. In this case, movable magnets are fitted onto the two ends of the yoke 1 1.

FIG. 11 depicts a modification of the embodiment of FIG. 9 wherein fixed magnet 40 is replaced by another movable magnet 50' provided with knob shaft 60'. While several embodiments of the invention have been shown and described, other variations will be readily apparent to those skilled in the art. Therefore, the invention is not limited to these embodiments but is intended to cover all such variations as may be within the scope of the invention defined by the following claims:

What is claimed is:

l. A raster distortion correcting reactor comprising an H-shaped core comprised of a pair of parallel, spaced yokes connected at their mid-sections by a coupling member, one of the yokes having wound thereon first and second coils, said coils each being divided into two coil parts and each coil part being constituted of a symmetrical winding on the yoke arms on opposite sides of said coupling member, the first coil being so constituted that, when electric current is caused to flow through it, magnetic fluxes generated in the two divided coil parts assume the same direction, while said second coil is so constituted that, when electric current is caused to flow through it, magnetic fluxes will be generated in opposite directions in the two divided coil parts.

2. A raster distortion correcting reactor in accordance with claim 1, and further comprising a fixed magnet mounted on one end of the H-shaped core, a disc-shaped movable magnet rotatably mounted on the other end of said core, said fixed magnet being fixed with one of its magnetic poles closely facing one end of the yoke of said core on which said coils are wound, and said disc shaped movable magnet being magnetized in the direction of its diameter with the face of the disc being arranged in such a manner that it directly touches both the other end of said yoke on which said coils are wound and the adjacent end of the other yoke.

3. A raster distortion correcting reactor in accordance with Claim 1 and further comprising two disc-shaped movable magnets rotatably mounted on the ends of said l-l-shaped core, said movable magnets being magnetized in the direction of their diameter and the disc surfaces being so arranged as to rotate in close contact with the ends of the two yokes of the abovementioned core.

4. A raster distortion correcting reactor in accordance with claim 1 and further comprising a first magnet fixedly mounted on one end of the H-shaped core and a second, disc-shaped movable magnet rotatably mounted on the other end of said core, said fixed magnet being fixed to one end of the coil-wound yoke of the core with its magnetic poles in close contact with the yoke end, said movable magnet having a central aperture and being magnetized in the direction of its diameter, and the other end of said coil wound yoke being telescoped into said central aperture of said movable magnet.

5. A raster distortion correcting reactor in accordance with claim 1 and further comprising two discshaped movable magnets magnetized in the direction of their diameters said magnets being arranged on the two ends of said l-l-shaped core, said movable magents each having apertures in the centers of the disc faces and beingrotatably mounted with said apertures in close contact with the ends of the coil-wound yoke of said 0 core. 

1. A raster distortion correcting reactor comprising an H-shaped core comprised of a pair of parallel, spaced yokes connected at their mid-sections by a coupling member, one of the yokes having wound thereon first and second coils, said coils each being divided into two coil parts and each coil part being constituted of a symmetrical winding on the yoke arms on opposite sides of said coupling member, the first coil being so constituted that, when electric current is caused to flow through it, magnetic fluxes generated in the two divided coil parts assume the same direction, while said second coil is so constituted that, when electric current is caused to flow through it, magnetic fluxes will be generated in opposite directions in the two divided coil parts.
 1. A raster distortion correcting reactor comprising an H-shaped core comprised of a pair of parallel, spaced yokes connected at their mid-sections by a coupling member, one of the yokes having wound thereon first and second coils, said coils each being divided into two coil parts and each coil part being constituted of a symmetrical winding on the yoke arms on opposite sides of said coupling member, the first coil being so constituted that, when electric current is caused to flow through it, magnetic fluxes generated in the two divided coil parts assume the same direction, while said second coil is so constituted that, when electric current is caused to flow through it, magnetic fluxes will be generated in opposite directions in the two divided coil parts.
 2. A raster distortion correcting reactor in accordance with claim 1, and further comprising a fixed magnet mounted on one end of the H-shaped core, a disc-shaped movable magnet rotatably mounted on the other end of said core, said fixed magnet being fixed with one of its magnetic poles closely facing one end of the yoke of said core on which said coils are wound, and said disc shaped movable magnet being magnetized in the direction of its diameter with the face of the disc being arranged in such a manner that it directly touches both the other end of said yoke on which said coils are wound and the adjacent end of the other yoke.
 3. A raster distortion correcting reactor in accordance with Claim 1 and further comprising two disc-shaped movable magnets rotatably mounted on the ends of said H-shaped core, said movable magnets being magnetized in the direction of their diameter and the disc surfaces being so arranged as to rotate in close contact with the ends of the two yokes of the above-mentioned core.
 4. A raster distortion correcting reactor in accordance with claim 1 and further comprising a first magnet fixedly mounted on one end of the H-shaped core and a second, disc-shaped movable magnet rotatably mounted on the other end of said core, said fixed magnet being fixed to one end of the coil-wound yoke of the core with its magnetic poles in close contact with the yoke end, said movable magnet having a central aperture and being magnetized in the direction of its diameter, and the other end of said coil wound yoke being telescoped into said central aperture of said movable magnet. 